Method for producing long retardation film

ABSTRACT

A method for producing a long retardation film having an optical axis in an oblique direction relative to the length direction of the long retardation film is provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for producing a longretardation film.

2. Description of the Related Art

From the past, in a liquid crystal display device or an organic ELdisplay device, an optical film such as a retardation film is used forthe purpose of the optical compensation thereof. For such an opticalfilm, a retardation film having an optical axis in an oblique directionrelative to the length direction of the film is sometimes used.

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1: JP-A-2003-240955

SUMMARY OF THE INVENTION

Industrial production of a retardation film having an optical axis in anoblique direction relative to the length direction of the film requiresa cumbersome processing technique, so that a new production method hasbeen demanded.

The present invention includes the following aspects.

[1] A method for producing a long retardation film, including, in thisorder:

(1) continuously applying an optical alignment membrane formingcomposition onto a long substrate to form a first application membraneon the long substrate;

(2) drying the first application membrane to form a first dried coatingmembrane;

(3) radiating a polarized light which is polarized in an obliquedirection relative to a length direction of the long substrate, onto thefirst dried coating membrane, so as to form a long optical alignmentmembrane in which a direction of an alignment restricting force isoblique relative to the length direction of the long substrate;

(4) continuously applying onto the long optical alignment membrane aliquid crystal cured membrane forming composition containing apolymerizable liquid crystal compound, so as to form a secondapplication membrane on the long optical alignment membrane;

(5) drying the second application membrane to form a second driedcoating membrane; and

(6) curing the second dried coating membrane to form a long retardationmembrane.

[2] The method for producing a long retardation film according to [1],further including, after the (6):

(7) transcribing the long retardation membrane or the long opticalalignment membrane and the long retardation membrane onto a longtranscription substrate via a pressure-sensitive adhesive agent, so asto obtain a long retardation film made of the long transcriptionsubstrate, a pressure-sensitive adhesive layer, and the long retardationmembrane or a long retardation film made of the long transcriptionsubstrate, a pressure-sensitive adhesive layer, the long retardationmembrane, and the long optical alignment membrane.

[3] The method for producing a long retardation film according to [1] or[2], wherein the polymerizable liquid crystal

compound is a compound represented by the following formula (A):

[X¹ represents an oxygen atom, a sulfur atom, or NR¹—; R¹ represents ahydrogen atom or an alkyl group having a carbon number of 1 to 4;

Y¹ represents a monovalent aromatic hydrocarbon group having a carbonnumber of 6 to 12 and optionally having a substituent or a monovalentaromatic heterocyclic group having a carbon number of 3 to 12 andoptionally having a substituent;

Q³ and Q⁴ each independently represent a hydrogen atom, a monovalentaliphatic hydrocarbon group having a carbon number of 1 to 20 andoptionally having a substituent, a monovalent alicyclic hydrocarbongroup having a carbon number of 3 to 20, a monovalent aromatichydrocarbon group having a carbon number of 6 to 20 and optionallyhaving a substituent, a halogen atom, a cyano group, a nitre group,—NR²R³, or —SR², or Q³ and Q⁴ are bonded with each other to form anaromatic ring or an aromatic heterocyclic ring together with carbonatoms to which these are bonded; R² and R³ each independently representa hydrogen atom or an alkyl group having a carbon number of 1 to 6;

D¹ and D² each independently represent a single bond, —C(═O)—O—,—C(═S)—O—, —CR⁴R⁵—, —CR⁴R⁵—CR⁶R⁷—, —O—CR⁴R⁵—, —CR⁴R⁵—O—CR⁶R⁷—,—CO—O—CR⁴R⁵—, —O—CO—CR⁴R⁵—, —CR⁴R⁵—O—CO—CR⁶R⁷—, —CR⁴R⁵—CO—O—CR⁶R⁷—,NR⁴—CR⁵R⁶—, or CO—NR⁴ 13 ;

R⁴, R⁵, R⁶, and R⁷ each independently represent a hydrogen atom, afluorine atom, or an alkyl group having a carbon number of 1 to 4;

G¹ and G² each independently represent a divalent alicyclic hydrocarbongroup having a carbon number of 5 to 8, where a methylene groupconstituting the alicyclic hydrocarbon group may be substituted with anoxygen atom, a sulfur atom, or NH—, and a methine group constituting thealicyclic hydrocarbon group may be substituted with a tertiary nitrogenatom; and

L¹ and L² each independently represent a monovalent organic group, whereat least one of L¹ and L² has a polymerizable group].

[4] A long retardation film including a long substrate, a long opticalalignment membrane, and a long retardation membrane in this order,wherein

a direction of an alignment restricting force of the long opticalalignment membrane is oblique relative to a length direction of the longsubstrate,

a thickness of the long retardation membrane is 3 μm or less, and

a direction of an optical axis of the long retardation membrane isoblique relative to the length direction of the long substrate.

[5] The long retardation film according to [4], having a wavelengthdispersion property satisfying the following formulas (1), (2), and (3):

Re(450)/Re(550)≦1.00   (1)

1.00≦Re(650)/Re(550)   (2)

100<Re(550)<160   (3)

wherein, in the formulas, Re(λ) represents an in-plane retardation valuerelative to a light having a wavelength of λ nm.

[6] A method for producing a long circularly polarizing plate,including, in this order: (1) continuously applying an optical alignmentmembrane forming composition onto a long substrate to form a firstapplication membrane on the long substrate;

(2) drying the first application membrane to form a first dried coatingmembrane;

(3) radiating a polarized light which is polarized in an obliquedirection relative to a length direction of the long substrate, onto thefirst dried coating membrane, so as to form a long optical alignmentmembrane in which a direction of an alignment restricting force isoblique relative to the length direction of the long substrate;

(4) continuously applying onto the long optical alignment membrane aliquid crystal cured membrane forming composition containing apolymerizable liquid crystal compound, so as to form a secondapplication membrane on the long optical alignment membrane;

(5) drying the second application membrane to form a second driedcoating membrane;

(6) curing the second dried coating membrane to form a long retardationmembrane; and

(8) bonding a long polarizing film onto the long retardation membrane.

[7] The method for producing a long circularly polarizing plateaccording to [6], further including, after the (8):

(9) peeling the long substrate or the long substrate and the longoptical alignment membrane off.

[8] The method for producing a long circularly polarizing plateaccording to [6] or [7], further including, after the (8) or (9):

(10) cutting the long circularly polarizing plate into pieces.

[9] A long circularly polarizing plate in which a long retardation filmaccording to [4] or [5] and a long polarizing film are stacked.

According to the present invention, a long retardation film having anoptical axis in an oblique direction relative to the length direction ofthe long retardation film can be produced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a model view illustrating an essential part of a continuousmethod (roll-to-roll form) for producing a long retardation film;

FIG. 2 is a model view illustrating a relationship between a directionD2 of an alignment restricting force of an optical alignment membraneand a length direction D1 of a long substrate;

FIG. 3 is a model view illustrating an essential part of a continuousmethod for producing a long circularly polarizing plate;

FIG. 4 is a model view illustrating an essential part of a productionmethod for peeling the long substrate or the long substrate and the longoptical alignment membrane off continuously from the long circularlypolarizing plate before taking up; and

FIG. 5 is a model view illustrating an essential part of a productionmethod for peeling the long substrate or the long substrate and the longoptical alignment membrane off continuously from the long circularlypolarizing pi ate after taking up.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

<Long Substrate>

The long substrate in the present invention does not include apolarizing element. Also, it Is preferable that the long substrate inthe present invention does not have a polarization property. The longsubstrate may be, for example, a plastic substrate. Examples of theplastic constituting the plastic substrate include polyolefins such aspolyethylene, polypropylene, and norbornene-based polymers; cyclicolefin-based resins; polyvinyl alcohol; polyethylene terephthalats;polymethacrylate; polyacrylate; cellulose esters such astriacetylcellulose, diacetylcellulose, and cellulose acetate propionate;polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone;polyetherketone; polyphenylene sulfide; and polyphenylene oxide. Theplastic is preferably a cellulose ester, a cyclic olefin-basedresin,polycarbonate, polyethylene terephthalate, or polymethacrylate.

A cellulose ester is one in which at least a part of the hydroxyl groupscontained in the cellulose are esterified, and is commerciallyavailable. The cellulose ester substrates also are commerciallyavailable. Examples of the commercially available cellulose estersubstrates include “FUJITAC (registered trademark) FILM” manufactured byFujifilm Corporation; and “KC8UX2M”, “KC8UY”, and “KC4UY” manufacturedby KONTCA MINOLTA OPTO, INC.; and others.

A cyclic olefin-based resin is constituted, for example, of a polymer ora copolymer (cyclic olefin-based resin) of cyclic olefins such asnorbornene or polycyclic norbornene-based monomers, and the cyclicolefin-based resin may partially contain an open ring moiety. Also, aresin obtained by hydrogenation of a cyclic olefin-based resincontaining an open ring moiety can be used as well. Further, the cyclicolefin-based resin may be, for example, a copolymer of a cyclic olefinand a chain olefin or a vinylated aromatic compound (styrene or thelike) from the viewpoint of not considerably deteriorating thetransparency or not considerably increasing the hygroscopicity. Also,the cyclic olefin-based resin may be such that a polar group isintroduced into the molecule thereof.

When the cyclic olefin-based resin is a copolymer of a cyclic olefin anda chain olefin or an aromatic compound having a vinyl group, the contentof the structural units deriving from the cyclic olefin is typically 50mol % or less, preferably within a range of 15 to 50 mol %, relative tothe total structural units of the copolymer. Examples of the chainolefin include ethylene and propylene, and examples of the aromaticcompound having a vinyl group include styrene, α-methylstyrene, andalkyl-substituted styrene. When the cyclic olefin-based resin is aterpolymer of a cyclic olefin, a chain olefin, and an aromatic compoundhaving a vinyl group, the content of the structural units deriving fromthe chain olefin is typically 5 to 80 mol % relative to the totalstructural units of the terpolymer, and the content of the structuralunits deriving from the aromatic compound having a vinyl group istypically 5 to 80 mol % relative to the total structural units of theterpolymer. Such a terpolymer provides an advantage of being able toreduce the amount of use of expensive cyclic olefins to a comparativelysmall amount in its production.

The cyclic olefin-based resins are commercially available. Examples ofthe commercially available cyclic olefin-based resins include “Topas”(registered trademark) manufactured by Ticona GmbH in Germany, “ARTON”(registered trademark) manufactured by JSR Corporation, “ZEONOR”(registered trademark) manufactured by ZEON CORPORATION, “ZEONEX”(registered trademark) manufactured by ZEON CORPORATION, and “APEL” (registered trademark ) manufactured by Mitsui Chemicals, Inc. Such acyclic olefin-based resin can be formed into a membrane by known meanssuch as the solvent-casting method or the melt-extrusion method, so asto produce a substrate. Also, a commercially available cyclicolefin-based resin substrate can be used as well. Examples of thecommercially available cyclic olefin-based resin substrates include“ESSINA” (registered trademark) manufactured by Sekisui Chemical Co.,Ltd., “SCA40” (registered trademark) manufactured by Sekisui ChemicalCo., Ltd., “ZEONOR FILM” (registered trademark) manufactured by OptesInc., and “ARTON FILM” (registered trademark) manufactured by JSR Co.,Ltd.

The thickness of the long substrate is preferably small from theviewpoint of having a weight of a degree such that practical handlingcan be made. However, when the thickness is too small, the strengthdecreases, thereby having a tendency of being inferior inprocessability. The thickness of the long substrate is typically 5 to300 μm, preferably 20 to 200 μm.

The length of the long substrate in the length direction is typically 10to 3000 m, preferably 100 to 2000 m. The length of the long substrate inthe lateral direction is typically 0.1 to 5 m, preferably 0.2 to 2 m.

<Optical Alignment Membrane Forming Composition>

The optical alignment membrane forming composition contains a polymer ora monomer having a photoreactive group and a solvent.

The photoreactive group refers to a group that generates a liquidcrystal alignment function by radiation of light. Specifically, aphotoreaction giving an origin of the liquid crystal alignment functionis generated, such as alignment induction of molecules or isomerizationreaction, dimerization reaction, photo crosslinking reaction, or photodecomposition reaction, that is generated by radiation of light. Amongthe photoreactive groups, those generating a dimerization reaction or aphoto crosslinking reaction are preferable because of being excellent inalignment property. The photoreactive group generating a reaction suchas described above is preferably one having an unsaturated bond,particularly a double bond, and a group having at least one selectedfrom the group consisting of carbon-carbon double bond (C═C bond),carbon-nitrogen double bond (C═N bond), nitrogen-nitrogen double bond(N═N bond), and carbon-oxygen double bond (C═O bond) is particularlypreferable.

Examples of the photoreactive group having a C═C bond include vinylgroup, polyene group, stilbene group, stilbazol group, stilbazoliumgroup, chalcone group, and cinnamoyl group. Examples of thephotoreactive group having a C═N bond include groups having a structuresuch as an aromatic Schiff base and an aromatic hydrazone. Examples ofthe photoreactive group having an N═N bond include azobenzene group,azonaphthalene group, aromatic heterocyclic azo group, bisazo group,formazan group, and those having azoxybenzene as a basic structure.Examples of the photoreactive group having a C═O bond includebenzophenone group, coumalin group, anthraquinone group, and maleimidegroup. These groups may have a substituent such as an alkyl group,alkoxy group, aryl group, allyloxy group, cyano group, alkoxycarbonylgroup, hydroxyl group, sulfonic acid group, or halogenated alkyl group.

Among these, a photoreactive group involved in photodimerizationreaction is preferable, and a cinnamoyl group and a chalcone group arepreferable because the amount of polarized light radiation needed foroptical alignment is comparatively small, and an optical alignmentmembrane being excellent in stability with heat and stability with lapseof time is easily obtained. As the polymer having a photoreactive group,those having a cinnamoyl group in which the terminal end part of thepolymer side chain thereof forms a cinnaraic acid structure areparticularly preferable.

As the solvent for the optical alignment membrane forming composition,those that dissolve polymers and monomers having a photoreactive groupare preferable. Examples of the solvents include water; alcohols such asmethanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol,methyl cellosolve, butyl cellosolve, and propylene glycol monomethylether; ester-based solvents such as ethyl acetate, butyl acetate,ethylene glycol methyl ether acetate, gamma-butyrolactone, propyleneglycol methyl ether acetate, and ethyl lactate; ketone-based solventssuch as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone,methyl amyl ketone, and methyl isobutyl ketone; non-chlorine-basedaliphatic hydrocarbon solvents such as pentane, hexane, and heptane;non-chlorine-based aromatic hydrocarbon solvents such as toluene andxylene; nitrile-based solvents such as acetonitrile; ether-basedsolvents such as tetrahydrofuran and dimethoxyethane; and chlorine-basedsolvents such as chloroform and chlorobenzene. These solvents may beused either singly or in combination.

The content of the polymer or monomer having a photoreactive grouprelative to the optical alignment membrane forming composition can besuitably adjusted in accordance with the kind of the polymer or monomerhaving a photoreactive group and the thickness of the optical alignmentmembrane that is to be produced; however, the content is preferably atleast 0.2 mass % or more, and a range of 0. 3 to 10 mass % isparticularly preferable. Also, polymer materials such as polyvinylalcohol or polyimide, or a photosensitizer may be contained within arange that does not considerably deteriorate the characteristics of theoptical alignment membrane.

<First Application Membrane>

A first application membrane is formed by applying the aforesaid opticalalignment membrane forming composition onto the long substrate.

The method for continuously applying the optical alignment membraneforming composition onto the long substrate may be, for example, thegravure coating method, the die coating method, the applicator method,the flexo method, or the like. Among these, the gravure coating method,the die coating method, and the flexo method are preferable.

<First Dried Coating Membrane>

A first dried coating membrane is formed by drying the first applicationmembrane. In the description of the present application, those in whichthe content of the solvent contained in the first application membranehas decreased to be 50 mass % or less are referred to as the first driedcoating membrane.

The method for drying the first application membrane may be, forexample, the natural drying method, the air drying method, the heateddrying method, the reduced-pressure drying method, or the like. A methodobtained by combination of the air drying method and the heated dryingmethod is preferably used. The drying temperature is preferably 10 to250° C., more preferably 25 to 200° C. The drying time is preferably 10seconds to 60 minutes, more preferably 30 seconds to 30 minutes. Bydrying, the solvent contained in the first application membrane isremoved.

The content of the solvent in the first dried coating membrane ispreferably 30 mass % or less, more preferably 10 mass % or less, stillmore preferably 5 mass % or less, and most preferably 1 mass % or less.

<Long Optical Alignment Membrane>

A long optical alignment membrane in which the direction of an alignmentrestricting force is oblique relative to the length direction of thelong substrate is obtained by radiating a polarized light which ispolarized in an oblique direction relative to the length direction ofthe long substrate, onto the first dried coating membrane.

The polarized light may be radiated either directly onto the first driedcoating membrane or after being transmitted through the long substrate.When the long substrate is formed of a material that absorbs thepolarized light, it is preferable that the polarized light is radiateddirectly onto the first dried coating membrane.

It is preferable that the polarized light is radiated in a directionperpendicular to the length direction and the lateral direction of thefirst dried coating membrane.

The wavelength of the polarized light is preferably within a wavelengthrange such that the photoreactive group in the polymer or monomer havinga photoreactive group can absorb light energy. Specifically, ultravioletray having a wavelength within a range of from 250 to 400 nm ispreferable.

A light source for the polarized light may be, for example, a xenonlamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp,a metal halide lamp, an ultraviolet ray laser such as KrF or ArF, or thelike. Among these, a high-pressure mercury lamp, an ultrahigh-pressuremercury lamp, and a metal halide lamp are preferable. These lamps arepreferable because the intensity of light emission of the ultravioletray having a wavelength of 313 nm is large.

The polarized light can be obtained, for example, by allowing the lightfrom the light source to pass through a polarizer. By adjusting thepolarization angle of the polarizer, the direction of the polarizationaxis of the polarized light can be adjusted in an arbitrary manner.Examples of the polarizers include a polarizing filter, a polarizingprism such as a Glan-Thompson prism or a Glan-Taylor prism, and apolarizer of wire grid type. It is preferable that the polarized lightis substantially a parallel light.

The alignment restricting force acts in a perpendicular direction or ina parallel direction relative to the direction of the polarization axisof polarized light. Therefore, by adjusting the polarization angle, thedirection of the alignment restricting force can be adjusted in anarbitrary manner. The angle formed by the direction of the polarizationaxis of the polarized light and the length direction of the longsubstrate is preferably 5° to 85°, more preferably 20° to 70°, stillmore preferably 30° to 60°, and most preferably 45°. Preferably, thedirection of the polarization axis of polarized light and the thicknessdirection of the long substrate are perpendicular to each other. Also,when masking is carried out at the time of radiating the polarizedlight, a plurality of different regions (patterns) can foe formed in theobtained direction of the alignment restricting force. Preferably, thelong optical alignment membrane has a uniform alignment pattern.

Thus, a long alignment film is obtained in which the long substrate andthe long optical alignment membrane are stacked, where the direction ofthe alignment restricting force of the long optical alignment membraneis oblique relative to the length direction of the long substrate.Preferably, the direction of the alignment restricting force of the longoptical alignment membrane and the thickness direction of the longsubstrate are perpendicular to each other.

The angle formed by the direction of the alignment restricting force andthe length direction of the long substrate is preferably 5° to 85°, morepreferably 20° to 70°, still more preferably 30° to 60°, and mostpreferably 45°.

The long optical alignment membrane preferably has a solvent resistanceof not being dissolved into a liquid crystal cured membrane formingcomposition at the time of applying the liquid crystal cured membraneforming composition. Also, the long optical alignment membranepreferably has a heat resistance in a heating process for drying oraligning a polymerizable liquid crystal compound. Further, it ispreferable that exfoliation or the like is not generated by friction orthe like at the time of transporting the long alignment film.

The membrane thickness of the long optical alignment membrane istypically 10 nm to 10000 nm, preferably 10 nm to 1000 nm, morepreferably 500 nm or less, and also more preferably 10 nm or more. Bysetting the membrane thickness to be within the above range, thealignment restricting force is sufficiently exhibited.

The long alignment film in which the long optical alignment membranehaving an alignment restricting force is formed on the long substratecan be used as an alignment film that induces alignment of a liquidcrystal material. Therefore, the long alignment film in which the longsubstrate and the long optical alignment membrane are stacked, where thedirection of the alignment restricting force of the optical alignmentmembrane is oblique relative to the length direction of the longsubstrate, is useful for production of a long retardation film in whichthe direction of the optical axis is oblique relative to the lengthdirection of the substrate, so that the long alignment film can be usedfor continuously producing a long retardation film.

<Liquid Crystal Cured Membrane Forming Composition>

The liquid crystal cured membrane forming composition in the presentinvention contains a polymerizable liquid crystal compound and asolvent.

The polymerizable liquid crystal compound is a compound having apolymerizable group and having a liquid crystal property. Thepolymerizable group refers to a group involved in polymerizationreaction, and is preferably a photopolymerizable group. Here, thephotopolymerizable group refers to a group capable of being involved inpolymerization reaction by an activated radical or acid generated from aphotopolymerization initiator described later. Examples of thepolymerizable groups include vinyl group, vinyloxy group, 1-chlorovinylgroup, isopropenyl group, 4-vinylphenyl group, acryloyloxy group,methacryloyloxy group, oxiranyl group, and oxetanyl group. Among these,acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranylgroup, and oxetanyl group are preferable, and acryloyloxy group is morepreferable. With regard to the liquid crystal property, the liquidcrystal may be either a thermotropic liquid crystal or a lyotropicliquid crystal, and also the thermotropic liquid crystal may be either anematic liquid crystal or a smectic liquid crystal.

As the polymerizable liquid crystal compound, a thermo tropic nematicliquid crystal is preferable from the viewpoint of facility inproduction.

A preferable polymerizable liquid crystal compound contained in theliquid crystal cured membrane forming composition may be, for example, acompound (which may hereafter be referred to as compound (A))represented by the following formula (A).

[In the formula (A), X¹ represents an oxygen atom, a sulfur atom, orNR¹—; R¹ represents a hydrogen atom or an alkyl group having a carbonnumber of 1 to 4;

Y¹ represents a monovalent aromatic hydrocarbon group having a carbonnumber of 6 to 12 and optionally having a substituent or a monovalentaromatic heterocyclic group having a carbon number of 3 to 12 andoptionally having a substituent;

Q³ and Q⁴ each independently represent a hydrogen atoms, a monovalentaliphatic hydrocarbon group having a carbon number of 1 to 20 andoptionally having a substituent, a monovalent alicyclic hydrocarbongroup having a carbon number of 3 to 20, a monovalent aromatichydrocarbon group having a carbon number of 6 to 20 and optionallyhaving a substituent, a halogen atom, a cyano group, a nitro group,—NR²R³, or —SR², or Q³ and Q⁴ are bonded with each other to form anaromatic ring or an aromatic heterocyclic ring together with carbonatoms to which these are bonded; R² and R³ each independently representa hydrogen atom or an alkyl group having a carbon number of 1 to 6;

D¹ and D² each independently represent a single bond, —C(—O)—O—,—C(—S)—O—, —CR⁴R⁵—, —CR⁴R⁵—CR⁶R⁷—, —O—CR⁴R⁵—, —CR⁴R⁵—O—CR⁶R⁷—,—CO—O—CR⁴R⁵—, —O—CO—CR⁴R⁵—, —CR⁴R⁵—O—CO—CR⁶R⁷—, —CR⁴R⁵—CO—O—CR⁶R⁷—,NR⁴—CR⁵R⁶—, or CO—NR⁴—;

R⁴, R⁵, R⁶, and R⁷ each independently represent a hydrogen atom, afluorine atom, or an alkyl group having a carbon number of 1 to 4;

G¹ and G² each independently represent a divalent alicyclic hydrocarbongroup having a carbon number of 5 to 8, where a methylene groupconstituting the alicyclic hydrocarbon group may be substituted with anoxygen atom, a sulfur atom, or NH—, and a methine group constituting thealicyclic hydrocarbon group may be substituted with a tertiary nitrogenatom; and

L¹ and L² each independently represent a monovalent organic group, whereat least one of L¹ and L² has a polymerizable group.]

L¹ in the compound (A) is preferably a group represented by the formula(A1), and L² is preferably a group represented by the formula (A2).

P¹-F¹-(B¹-A¹)_(k)-E¹-   (A1)

P²-F²-(E²-A²)_(l)-E²-   (A2)

[In the formulas (A1) and (A2),

B¹, B², E¹, and E² each independently represent —CR⁴R⁵—, —CH²—CH²—, —O—,—S—, —CO—O—, —O—CO—O—, —CS—O—, —O—CS—O—, —CO—NR¹—, —O—CH₂—, —S—CH₂—, ora single bond;

A¹ and A² each independently represent a divalent alicyclic hydrocarbongroup having a carbon number of 5 to 8 or a divalent aromatichydrocarbon group having 3 carbon number of 6 to 18, where a methylenegroup constituting the alicyclic hydrocarbon group may be substitutedwith an oxygen atom, a sulfur atom, or NH—, and a methine groupconstituting the alicyclic hydrocarbon group may be substituted with atertiary nitrogen atom;

k and l each independently represent an integer of 0 to 3;

F¹ and F² represent a divalent aliphatic hydrocarbon group having acarbon number of 1 to 12;

P¹ represents a polymerizable group;

P² represents a hydrogen atom or a polymerizable group; and

R⁴ and R⁵ each independently represent a hydrogen atom, a fluorine atom,or an alkyl group having a carbon number of 1 to 4. ]

A preferable compound (A) is a polymerizable liquid crystal compounddisclosed in JF-A-2011-207765.

Specific examples of the polymerizable liquid crystal compounds includecompounds having a polymerizable group among the compounds disclosed in“3.8.6 Nettowaku (Network) (Kanzen Kakyo-gata (complete cross linkingtype))”, “6.5.1 Ekisho Zairyo (Liquid Crystal Materials) b. JyugoseiNemachikku Ekisho Zairyo (Polymerizable Hematic Liquid CrystalMaterials)” of Ekisho Einran (Liquid Crystal Handbook) (edited by EkishoBinran Henshu Iinkai (Liquid Crystal Handbook Editorial Committee),issued by Maruzen Co., Ltd. on Oct. 30, 2000).

When the liquid crystal cured membrane forming composition contains theabove compound (A), the liquid crystal cured membrane formingcomposition may further contain a polymerizable liquid crystal compoundthat is different from the compound (A).

Examples of the polymerizable liquid crystal compounds different fromthe compound (A) include a compound (which may hereafter referred to as“compound (6)”) having a group represented by the formula (6).

P¹¹-B¹¹-E¹¹-B¹²-A¹¹-B¹³-   (6)

(in the formula (6), P¹¹ represents a polymerizable group;

A¹¹ represents a divalent alicyclic hydrocarbon group or a divalentaromatic hydrocarbon group; a hydrogen atom contained in the divalentalicyclic hydrocarbon group and the divalent aromatic hydrocarbon groupmay be substituted with a halogen atom, an alkyl group having a carbonnumber of 1 to 6, an alkoxy group having a carbon number of 1 to 6, acyano group, or a nitro group; a hydrogen atom contained in the alkylgroup having a carbon number of 1 to 6 and the alkoxy group having acarbon number of 1 to 6 may be substituted with a fluorine atom;

B¹¹ represents —O—, —S—, —CO—O—, —O—CO—, —O—CO—O—, —CO—NR¹⁶—, —NR¹⁶—CO—,—CO—, —CS—, or a single bond; R¹⁶ represents a hydrogen atom or an alkylgroup having a carbon number of 1 to 6;

B¹² and B¹³ each independently represent —C↓C—, —CH═CH—, —CH₂—CH₂—, —O—,—S—, —C(═O)—, —C(═O)—O—, —O—C—(═O)—, —O—C(═O)—O—, —CH═N—, —N═CH—, —N═N—,—C(═O)—NR¹⁶—, —NR¹⁶—C(═O)—, —OCH₂—, —OCF₂—, —CH₂O—, —CF₂O—,—CH═CH—C(═O)—O—, —O—C(═O)—CH═CH—, or a single bond;

E¹¹ represents an alkylene group having a carbon number of 1 to 12, anda hydrogen atom contained in the alkylene group may be substituted withan alkyl group having a carbon number of 1 to 5 or an alkoxy grouphaving a carbon number of 1 to 5; a hydrogen atom contained in the alkylgroup and the alkoxy group may be substituted with a halogen atom, and—CH₂ — contained in the alkylene group may be substituted with —O— or—CO—.)

Because photopolymerization, for example, is used in order to cure theretardation plate, P¹¹ is preferably a radical-polymerizable group or acationic-polymerizable group suitable for photopolymerization. Inparticular, P¹¹ is preferably a group represented by the followingformulas (P-1) to (P-5) because of the facility in handling and facilityin production.

[In the formulas (P-1) to (P-5), R¹⁷ to R²¹ each independently representan alkyl group having a carbon number of 1 to 6 or a hydrogen atom,and * represents a bonding hand with B¹¹.]

P¹¹ is preferably a group represented by the formulas (P-4) to (P-10),and examples thereof include vinyl group, p-(2-phenylethenyl)phenylgroup, oxiranyl group, oxetanyl group, isocyanate group, andisothiocyanate group.

More preferably, P¹¹-B¹¹- is an acryloyloxy group or a methacryloyloxygroup.

The carbon number of the aromatic hydrocarbon group and the alicyclichydrocarbon group of A¹¹ may be, for example, 3 to 18, preferably 5 to12, and more preferably 5 or 6. A¹¹ is preferably a 1,4-cyclohexylenegroup or a 1,4-phenylene group.

E¹¹ is preferably an alkylene group having a carbon number of 1 to 12and not branched into two or more, and —CH₂— contained in the alkylenegroup may be substituted with —O—.

Specific examples thereof include methylene group, ethylene group,propylene group, butylene group, pentylene group, hexylene group,heptylene group, octylene group, nonylene group, decalene group,undecalene group, dodecylene group, —CH₂—CH₂—O—CH₂—CH₂—,—CH₂—CH₂—O—CH₂—CH₂—O—CH₂—CH₂—, and—CH₂—CH₂—O—CH₂—CH₂—O—CH₂—CH₂—O—CH₂—CH₂—.

The compound (6) maybe, for example, a compound represented by theformula (I), (II), (III), (IV), (V), or (VI).

P¹¹-B¹¹-E¹¹-B¹²-A¹¹-B¹³-A¹²-B¹⁴-A¹³-B¹⁵-A¹⁴-B¹⁶-E¹²-B¹⁷P¹²   (I)

P¹¹-B¹¹-E¹¹-B¹²-A¹¹-B¹³-A¹²-B¹⁴-A¹³-B¹⁵-A¹⁴-F¹¹   (II)

P¹¹-B¹¹-E¹¹-B¹²-A¹¹-B¹³-A¹²-B¹⁴-A¹³-B¹⁵-E¹²-B¹⁷-P¹²   (III)

P¹¹-B¹¹-E¹¹-B¹²-A¹¹-B¹³-A¹²-B¹⁴-A¹³-F¹¹   (IV)

P¹¹-B¹¹-E¹¹-B¹²-A¹¹-B¹³-A¹²-B¹⁴-E¹²-B¹⁷-P¹²   (V)

P¹¹-B¹¹-E¹¹-B¹²-A¹¹-B¹³-A¹²-F¹¹   (VI)

(In the formulas, A¹² to A¹⁴ have the same meaning as A¹¹; B¹⁴ to B¹⁶have the same meaning as B¹²; B¹⁷ has the same meaning as B¹¹; E¹² hasthe same meaning as E¹¹;

F¹¹ represents a hydrogen atom, an alkyl group having a carbon number of1 to 13, an alkoxy group having a carbon number of 1 to 13, a nitritegroup, a nitro group, a trifluoromethyl group, a dimethylamino group, ahydroxy group, a hydroxymethyl group, a formyl group, a sulfo group, acarboxy group, a carboxyl group esterified with an alcohol having acarbon number of 1 to 10, or a halogen atom; and —CH₂— contained in thealkyl group and the alkoxy group may be substituted with —O—.)

Specific examples of the compound (6) include the compounds representedby the following formulas. Here, in the formulas, k1 and k2 represent aninteger of 2 to 12. These liquid crystal compounds are preferablebecause of being readily obtainable such as being easily synthesizableor being commercially available.

Specific examples of the polymerizable liquid crystal compoundsdifferent from the compound (A) include compounds having a polymerizablegroup among the compounds disclosed in 3.2 Men Kiraru Bojyo EkishoBunshi (Non-chiral Rod-shaped Liquid Crystal Molecules) and 3.3 KiraruBojyo Ekisho Bunshi (Chiral Rod-shaped Liquid Crystal Molecules) ofChapter 3 Bunshikozo To Ekishosei (Molecular Structure And LiquidCrystallinity) of Ekisho Binran (Liquid Crystal Handbook) (edited byEkisho Binran Henshu Iinkai (Liquid Crystal Handbook EditorialCommittee), issued by Maruzen Co., Ltd. on Oct. 30, 2000).

When the liquid crystal cured membrane forming composition contains thecompound (A) and polymerizable liquid crystal compounds different fromthe compound (A) as the polymerizable liquid crystal compound, thecontent of the polymerizable liquid crystal compounds different from thecompound (A) is preferably 90 parts by mass or less relative to 100parts by mass of the polymerizable liquid crystal compound.

The content of the polymerizable liquid crystal compound in the liquidcrystal cured membrane forming composition is typically 70 to 99.5 partsby mass, preferably 80 to 99 parts by mass, more preferably 80 to 94parts by mass, and still more preferably 80 to 90 parts by mass,relative to 100 parts by mass of the solid component of the liquidcrystal cured membrane forming composition. When the content of thepolymerizable liquid crystal compound is within the above range, thealignment property tends to be enhanced. Here, the solid componentrefers to a sum amount of the components of the liquid crystal curedmembrane forming composition excluding the solvent.

The solvent is preferably one that can completely dissolve thepolymerizable liquid crystal compound, and is preferably a solvent thatis inactive to the polymerization reaction of the polymerizable liquidcrystal compound.

Examples of the solvent include alcohol solvents such as methanol,ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethyleneglycol methyl ether, ethylene glycol butyl ether, and propylene glycolmonomethyl ether; ester solvents such as ethyl acetate, butyl acetate,ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycolmethyl ether acetate, and ethyl lactate; ketone solvents such asacetone, methyl ethyl ketone, cyclopentanone, cyclohexanone,2-heptanone, and methyl isobutyl ketone; aliphatic hydrocarbon solventssuch as pentane, hexane, and heptane; aromatic hydrocarbon solvents suchas toluene and xylene; nitrile solvents such as acetonitrile; ethersolvents such as tetrahydrofuran and dimethoxyethane;chlorine-containing solvents such as chloroform and chlorobenzene; andlactam-based solvents such as N-methyl-2-pyrrolidone. These solvents maybe used either singly or in combination.

The content of the solvent is preferably 50 to 98 mass % relative to thetotal amount of the liquid crystal cured membrane forming composition.In other words, the content of the solid component in the liquid crystalcured membrane forming composition is preferably 2 to 50 mass %. Whenthe content of the solid component is 50 mass % or less, the viscosityof the liquid crystal cured membrane forming composition becomes low, sothat the thickness of the liquid crystal cured membrane becomesapproximately uniform, thereby giving a tendency such that unevenness isless likely to be generated in the liquid crystal cured membrane. Also,the content of the solid component such as this can be determined inconsideration of the thickness of the liquid crystal cured membrane thatis to be produced.

The liquid crystal cured membrane forming composition may contain apolymerization initiator, a sensitizer, a polymerization inhibitor, alevelling agent, and a polyraerizable non-liquid-crystal compound ascomponents other than the polymerizable liquid crystal compound and thesolvent.

(Polymerization Initiator)

The liquid crystal cured membrane forming composition typically containsa polymerization initiator. The polymerization initiator is a compoundthat can start the polymerization reaction of the polymerizable liquidcrystal compound or the like. The polymerization initiator is preferablya photopolymerization initiator that generates active radicals by actionof light.

Examples of the polymerization initiator include a benzoin compound, abenzophenone compound, an alkylphenone compound, an acylphosphine oxidecompound, a triazine compound, an iodonium salt, and a sulfonium salt.

Examples of the benzoin compound include benzoin, benzoin methyl ether,benzoin ethyl ether, benzoin i sop ropy 1 ether, and benzoin isobutylether.

Examples of the benzophenone compound include benzophenone, methylo-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4′-methyldiphenylsulfide, 3,3′,4,4′-tetra(tert-butylperoxycarbonyl)benzophenone, and2,4,6-trimethylbenzophenone.

Examples of the alkylphenone compound include oligomers ofdiethoxyacetophenone,2-methyl-2-morpholino-1-(4-methylthiophenyl)propane-1-one,2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butane-1-one,2-hydroxy-2-methyl-1-phenylpropane-1-one,1,2-diphenyl-2,2-dimethoxyethane-1-one,2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propane-1-one,1-hydroxycyclohexyl phenyl ketone, and2-hydroxy-2-methyl-1-[(4-(1-methylvinyl)phenyl]propane-1-one.

Examples of the acylphosphine oxide compound include2,4,6-trimethylbenzoyldiphenylphosphine oxide andbis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

Examples of the triazine compound include2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine,2,4-bis(trichloromethyl)-6-(4-methoxynaphthyl)-1,3,5-triazine,2,4-bis(trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine,2,4-bis(trichloromethyl)-6-[2-(5-methylfuran-2-yl)ethenyl]-1,3,5-triazine,2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)ethenyl]-1,3,5-triazine,2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)ethenyl]-1,3,5-triazine, and2,4-bis(trichloromethyl)-6-[2-(3,4-dimethoxyphenyl)ethenyl]-1,3,5-triazine.

As the polymerization initiator, a commercially available one can beused. Examples of the commercially available polymerization initiatorsinclude “Irgacure (registered trademark) 907”, “Irgacure (registeredtrademark) 184”, “Irgacure (registered trademark) 651”, “Irgacure(registered trademark) 819”, “Irgacure (registered trademark) 250”, and“Irgacure (registered trademark) 369” manufactured by Chiba Japan Co.,Ltd.; “SEIKUOL (registered trademark) BZ”, “SEIKUOL (registeredtrademark) Z”, and “SEIKUOL (registered trademark) BEE” manufactured bySeiko Chemical Co., Ltd.; “kayacure (registered trademark) BP100”manufactured by Nippon Kayaku Co., Ltd.; “kayacure (registeredtrademark) UVT-6992” manufactured by Dow Chemical Company; “AdekaoptomerSP-152” and “Adekaoptomer SP-170” manufactured by ADEKA CORPORATION;“TAS-A” and “TAZ-PP” manufactured by Nihon SiberHegner K.K.; and“TAS-104” manufactured by SANWA Chemical Co., Ltd.

The content of the polymerization initiator in the liquid crystal curedmembrane forming composition can be suitably adjusted in accordance withthe kind of the polymerizable liquid crystal compound and the amountthereof; however, the content is typically 0.1 to 30 parts by mass,preferably 0.5 to 10 parts by mass, more preferably 0.5 to 8 parts bymass, relative to 100 parts by mass of the content of the polymerizableliquid crystal compound. When the content of the polymerizationinitiator is within this range, the alignment of the polymerizableliquid crystal compound is not disturbed, so that it is preferable.

(Sensitizer)

The liquid crystal cured membrane forming composition may furthercontain a sensitizer. The sensitizer is preferably a photosensitizer.Examples of the sensitizer include xanthone compounds such as xanthoneand thioxanthone (for example, 2,4-diethylthioxanthone,2-isopropylthioxanthone, and the like); anthracene compounds such asanthracene and alkoxy-containing anthracene (for example,dibutoxyanthracene and the like); phenothiazine; and rubrene.

When the liquid crystal cured membrane forming composition contains asensitizer, the polymerization reaction of the polymerizable liquidcrystal compound contained in the liquid crystal cured membrane formingcomposition can be further promoted. The amount of use of such asensitizer is preferably 0.1 to 30 parts by mass, more preferably 0.5 to10 parts by mass, and still more preferably 0.5 to 8 parts by mass,relative to 100 parts by mass of the content of the polymerizable liquidcrystal compound.

(Polymerization Inhibitor)

The liquid crystal cured membrane forming composition may furthercontain a polymerization inhibitor. When a polymerization inhibitor iscontained, the degree of progression of the polymerization reaction ofthe polymerizable liquid crystal compound can be controlled, and thepolymerization reaction can be allowed to proceed in a stable manner.

Examples of the polymerization inhibitor include radical scavengers suchas hydroquinone, alkoxy-containing hydroquinone, alkoxy-containingcatechol (for example, butylcatechol or The like), pyrogallol, and2,2,6,6-tetramethyl-1-piperidinyloxy radical; thiophenols;β-naphthylamines; and β-naphthols.

When a polymerization inhibitor is contained in the liquid crystal curedmembrane forming composition, the content thereof is preferably 0.1 to30 parts by mass, more preferably 0.5 to 10 parts by mass, and stillmore preferably 0.5 to 8 parts by mass, relative to 100 parts by mass ofthe content of the polymerizable liquid crystal compound. When thecontent of the polymerization inhibitor is within this range, thepolymerization can be allowed to proceed without disturbing thealignment of the polymerizable liquid crystal compound, so that it ispreferable.

(Levelling Agent)

A levelling agent may foe contained in the liquid crystal cured membraneforming composition. A levelling agent has a function of adjusting thefluidity of the liquid crystal cured membrane forming composition andmaking the membrane obtained by applying the liquid crystal curedmembrane forming composition be more smooth and flat, and may be, forexample, a surfactant. Preferable examples of the levelling agentinclude levelling agents containing a polyacrylate compound as a majorcomponent and levelling agents containing a fluorine-atom-containingcompound as a major component.

Examples of the levelling agents containing a polyacrylate compound as amajor component include “BYK-350”, “BYK-352”, “BYK-353”, “BYK-354”,“BYK-355”, “BYK-358N”, “BYK-361N”, “BYK-380”, “BYK-381”, and “BYK-392”manufactured by BYK-Chemie GmbH.

Examples of the levelling agents containing a fluorine-atom-containingcompound as a major component include “MEGAFAC (registered trademark;R-08”, “MEGAFAC (registered trademark) R-30”, “MEGAFAC (registeredtrademark) R-90”, “MEGAFAC (registered trademark) F-410”, “MEGAFAC(registered trademark) F-411”, “MEGAFAC (registered trademark) F-443”,“MEGAFAC (registered trademark) F-445”, “MEGAFAC (registered trademark)F-470”, “MEGAFAC (registered trademark) F-471”, “MEGAFAC (registeredtrademark) F-477”, “MEGAFAC (registered trademark) F-479”, “MEGAFAC(registered trademark) F-482”, and “MEGAFAC (registered trademark)F-483” manufactured by DIC Corporation; “SURFLON (registered trademark)S-381”, “SURFLON (registered trademark) S-382”, “SURFLON (registeredtrademark) S-383”, “SURFLON (registered trademark) S-393”, “SURFLON(registered trademark) SC-101”, “SURFLON (registered trademark) SC-105”,“SURFLON (registered trademark) KK-40”, and “SURFLON (registeredtrademark) SA-100” manufactured by AGC Seimi Chemical Co., Ltd.; “E1830”and “E5844” manufactured by Daikin Fine Chemical Laboratory Co., Ltd.;and “EFTOP EF301”, “EFTOP EF303”, “EFTOP EF351”, and “EFTOP EF352”manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.

When a levelling agent is contained in the liquid crystal cured membraneforming composition, the content thereof is preferably 0.01 parts bymass or more and 5 parts by mass or less, more preferably 0.05 parts bymass or more and 3 parts by mass or less, relative to 100 parts by massof the content of the polymerizable liquid crystal compound. When thecontent of the levelling agent is within this range, it is easy to makethe polymerizable liquid crystal compound be horizontally aligned, andthe obtained present liquid crystal cured membrane tends to be moresmooth and flat, so that it is preferable. When the content of thelevelling agent relative to the polymerizable liquid crystal compoundexceeds the aforementioned range, unevenness is liable to be generatedin the obtained present liquid crystal cured membrane, so that it is notpreferable. Here, the liquid crystal cured membrane forming compositionmay contain two or more kinds of the levelling agents.

(Polymerizable Non-Liquid-Crystal Compound)

The liquid crystal cured membrane forming composition may contain apolymerizable non-liquid-crystal compound. When a polymerizablenon-liquid-crystal compound is contained, the crosslinking density ofthe polymerization reactive sites is enhanced, whereby the strength ofan optical anisotropic layer can be improved.

The polymerizable non-liquid-crystal compound preferably has at leastone polymerizable group selected from the group consisting of anacryloyl group, a methacryloyl group, and an isocyanate group. Morepreferably, the polymerizable non-liquid-crystal compound has two ormore and ten or less polymerizable groups, still more preferably threeor more and eight or less polymerizable groups.

When the liquid crystal cured membrane forming composition contains apolymerizable non-liquid-crystal compound, the content thereof istypically 0.1 parts by mass to 30 parts by mass, preferably 0.5 parts bymass to 10 parts by mass, relative to 100 parts by mass of thepolymerizable liquid crystal compound.

The viscosity of the liquid crystal cured membrane forming compositionis preferably 10 mPa·s or less, more preferably 0.1 to 7 mPa·s.

When the viscosity is within the aforesaid range, unevenness in themembrane thickness of the second application membrane is less likely tofoe generated.

<Second Application Membrane>

A second application membrane is formed by applying the liquid crystalcured membrane forming composition onto the long optical alignmentmembrane.

A method of continuously applying the liquid crystal cured membraneforming composition onto the long optical alignment membrane may be, forexample, a method similar to that of applying the optical alignmentmembrane forming composition.

<Second Dried Coating Membrane>

A second dried coating membrane Is formed by drying the secondapplication membrane. In the description of the present application, thesecond dried coating membrane refers to one in which the content of thesolvent in the second application membrane has decreased to be 50 mass %or less. The content of the solvent is preferably 30 mass % or less,more preferably 10 mass % or less, still more preferably 5 mass % orless, and most preferably 1 mass % or less.

The method of drying the second application membrane, the dryingtemperature, and the drying time may be, for example, similar to thoseof the first application membrane.

When the polymerizable liquid crystal compound contained in the seconddried coating membrane after drying does not form a liquid crystalphase, the liquid crystal phase can be formed by heating the seconddried coating membrane up to a temperature at which the polymerizableliquid crystal compound exhibits a liquid crystal phase. The liquidcrystal phase maybe formed by heating the polymerizable liquid crystalcompound contained in the second dried coating membrane to or above atemperature of transition to a solution state and subsequently coolingthe polymerizable liquid crystal compound to a temperature at which thepolymerizable liquid crystal compound exhibits a liquid crystal phase.

Here, the above drying and the heating for forming the above liquidcrystal phase may be carried out through the same

heating step.

<Long Retardation Membrane>

A long retardation membrane is formed by curing the second dried coatingmembrane.

A retardation membrane has optical functions such as absorption,reflection, diffraction, scattering, refraction, and birefringence. Inparticular, the retardation membrane is used for converting linearlypolarized light into circularly polarized light or ellipticailypolarized light, or conversely, converting circularly polar i zed light,or ellipticaily polarized light into linearly polarized light.

To cure is, in other words, to polymerize the polymerizable liquidcrystal compound contained in the second dried coating membrane. Apolymerizing method may be, for example, a heating method or a method ofradiating light, and is preferably a method of radiating light.

The light may be radiated directly onto the second dried coatingmembrane or radiated after being transmitted through the long substrate.When the long substrate is made of a material that absorbs light, it ispreferable that the light is radiated directly onto the second driedcoating membrane.

Curing is preferably carried out in a state in which the liquid crystalphase is formed in the polymerizable liquid crystal compound. The curingmay be carried out by radiating light at a temperature at which theliquid crystal phase is exhibited.

The light for radiation of light maybe, for example, visible light,ultraviolet light, or laser light. From the viewpoint of facility inhandling, ultraviolet light is preferable. The light may be radiatedeither directly onto the second dried coating membrane or after beingtransmitted through the long substrate.

A light source for the radiation of light maybe, for example, a xenonlamp, a high-pressure mercury lamp, an ultra high-pressure mercury lamp,a metal halide lamp, an ultraviolet ray laser such as KrF or ArF, or thelike. Among these, a high-pressure mercury lamp, an ultrahigh-pressuremercury lamp, and a metal halide lamp are preferable. These lamps arepreferable because the intensity of light emission of the ultravioletlight having a wavelength of 313 nm is large.

The thickness of the long retardation membrane is typically 3 μm orless, and is preferably within a range of 0.5 μm or more and 3 μm orless, more preferably within a range of 1 μm or more and 3 μm or less.The thickness of the long retardation membrane can be measured by usingan interference membrane thickness gauge, a laser microscope, or acontact-type membrane thickness gauge.

Thus, a long retardation film is obtained having a long substrate, along optical alignment membrane, and a long retardation membrane in thisorder, where the direction of the alignment restricting force of thelong optical alignment membrane is oblique relative to the lengthdirection of the long substrate, and the direction of the optical axisof the long retardation membrane is oblique relative to the lengthdirection of the long substrate and parallel to the direction of theoptical alignment restricting force.

The direction of the optical axis of the long retardation membrane ispreferably 5° to 85°, more preferably 20° to 70°, still more preferably30° to 50°, and most preferably 45°, relative to the length direction ofthe long substrate.

The aforesaid long retardation film preferably has a wavelengthdispersion property satisfying the following formulas (1), (2), and (3).By forming a liquid crystal cured membrane from the liquid crystal curedmembrane forming composition containing the above compound (A), a longretardation film having the aforesaid wavelength dispersion property canbe obtained.

Re(450)/Re(550)<1.00   (1)

1.00≦Re(650)/Re(550)   (2)

100<Re(550)−160   (3)

(In the formulas, Re(λ) represents an in-plane retardation valuerelative to a light having a wavelength of λ nm.)

The wavelength dispersion property of the long retardation film can bedetermined in accordance with the content of the compound (A) containedin the liquid crystal cured membrane forming composition.

Specifically, about two to five kinds of compositions each having adifferent content of the compound (A) may be prepared; a retardationmembrane having the same membrane thickness may be produced from each ofthe compositions; the retardation value of the obtained retardationmembrane may be determined; correlation between the content of thecompound (A) and the retardation value of the retardation membrane maybe determined from the result thereof; and the content of the compound(A) needed for giving a desired retardation value may be determined fromthe obtained correlationship.

The long retardation membrane contained in the obtained long retardationfilm may be transcribed onto a long transcription substrate via apressure-sensitive adhesive agent, thereby to obtain a long retardationfilm made of the long transcription substrate, a pressure-sensitiveadhesive layer, and the long retardation membrane.

The long optical alignment membrane and the long retardation membranecontained in the obtained long retardation film may be transcribed ontoa long transcription substrate via a pressure-sensitive adhesive agent,thereby to obtain a long retardation film made of the long transcriptionsubstrate, a pressure-sensitive adhesive layer, the long retardationmembrane, and the long optical alignment membrane.

As the pressure-sensitive adhesive agent, a known one may be used, andthe transcription may be carried out by a known method. The longtranscription substrate may be, for example, the same one as the longsubstrate.

A long circularly polarizing plate may be produced by integrallylaminating (bonding) a general long polarizing film onto the longretardation film of the present invention.

By setting the direction of the optical axis of the long retardationmembrane to be 45° relative to the length direction of the longsubstrate, the productivity of the long circularly polarizing plateobtained by integral lamination of the long retardation film of thepresent invention and the long polarizing film is improved.

The long substrate maybe peeled off from the long circularly polarizingplate made of the long substrate, the long optical alignment membrane,the long retardation membrane, and the long polarizing film, thereby toobtain a long circularly polarizing plate made of the long opticalalignment membrane, the long retardation membrane, and the longpolarizing film.

The long substrate and the long optical alignment membrane may be peeledoff from the long circularly polarizing plate made of the longsubstrate, the long optical alignment membrane, the long retardationmembrane, and the long polarizing film, thereby to obtain a longcircularly polarizing plate made of the long retardation membrane andthe long polarizing film.

A pressure-sensitive adhesive layer may be disposed on either surface ofthe obtained long circularly polarizing plate.

A retardation film is obtained by cutting the obtained long retardationfilm into pieces. Also, a circularly polarizing plate is obtained bycutting the long circularly polarizing plate into pieces.

Cutting into pieces excludes a case in which the balance between thelonger side and the shorter side of the film is considerablyextraordinary and, in the description of the present application, a formof “pieces” refers to a case in which the length or the longer side isfive times or less as large as the length of the shorter side.

The cutting can be carried out by an arbitrary method.

<Method for Continuously Producing a Long Retardation Film>

The long retardation film of the present invention is preferablyproduced continuously in a roll-to-roll form. With reference to FIG. 1,an essential part of the method for continuously producing a longretardation film in a roll-to-roll form will be described.

A first roll 210 in which a long substrate is taken up on a first rollcore 210A may be commercially available. The long substrate commerciallyavailable in such a roll form may be, for example, a film made ofcellulose ester, cyclic olefin-based resin, polyethylene terephthalate,or polymethacrylate among the long substrates already exemplified.

Subsequently, the long substrate is paid out from the first roll 210.The method of paying out the long substrate is carried out by placing asuitable rotation means on the roll core 210A of the first roll 210 androtating the first roll 210 by the rotation means. Also, a method maybeadopted in which a suitable auxiliary roll 300 is placed in a directionof transporting the long substrate from the first roll 210, and the longsubstrate is paid out by a rotation means of the auxiliary roll 300.Further, a method may foe adopted in which a rotation means is placed onboth of the first roll core 210A and the auxiliary roll 300, whereby thelong substrate is paid out while a suitable tension is being imparted tothe long substrate.

The long substrate paid out from the first roll 210 is subjected toapplication of the optical alignment membrane forming composition by anapplication apparatus 211A on the surface thereof when passing throughthe application apparatus 211A. The application apparatus 211A forcontinuously applying the optical alignment membrane forming compositionin this manner is preferably in accordance with the gravure coatingmethod, the die coating method, or the flexo method.

The long substrate on which the first application membrane has beenformed by passing through the application apparatus 211A is transportedto a drying furnace 212A, and the first application membrane is dried bythe drying furnace 212A to form a first dried coating membrane. As thedrying furnace 212A, a hot-air type drying furnace obtained bycombination of the air drying method and the heated drying method isused, for example. The set temperature of the drying furnace 212A isdetermined in accordance with the kind of the solvent contained in theoptical alignment membrane forming composition or the like. Also, thedrying furnace 212A may be made of a plurality of zones having settemperatures that are different from each other, or may be a seriesconnection of a plurality of drying furnaces having set temperaturesthat are different from each other.

A long optical alignment membrane is obtained by radiating polarizedlight onto the obtained first dried coating membrane by a polarizedlight radiating apparatus 213A. At this time, the polarized light isradiated so that the direction D2 of the alignment restricting force ofthe optical alignment membrane will be oblique relative to the lengthdirection D1 of the long substrate. FIG. 2 is a model view illustratinga case in which the relationship between the direction D2 of thealignment restricting force of the optical alignment membrane formedafter the polarized light radiation and the length direction D1 of thelong substrate is 45°. In other words, FIG. 2 shows that the angleformed by the length direction D1 of the long substrate and thedirection D2 of the alignment restricting force of the long opticalalignment membrane is 45° when the surface of the long optical alignmentmembrane after passing through the polarized light radiating apparatus213A is viewed.

Subsequently, the long substrate on which the long optical alignmentmembrane has been formed passes through an application apparatus 211B.By the application apparatus 211B, a liquid crystal cured membraneforming composition is applied onto the long optical alignment membrane,so as to form a second application membrane. Thereafter, the longsubstrate is passed through a drying furnace 212B to form a second driedcoating membrane. In the same manner as the drying furnace 212A, thedrying furnace 212B may be made of a plurality of zones having settemperatures that are different from each other or may be a seriesconnection of a plurality of drying furnaces having set temperaturesthat are different from each other.

By passing through the drying furnace 212B, the polymerizable liquidcrystal compound contained in the liquid crystal cured membrane formingcomposition forms a liquid crystal phase. By radiating light with use ofa polarized light radiating apparatus 213B in a state in which thepolymerizable liquid crystal compound contained in the second driedcoating membrane has formed the liquid crystal phase, the polymerizableliquid crystal compound is polymerized while retaining the liquidcrystal phase, thereby to form a retardation membrane.

The long retardation film thus obtained is taken up by a second rollcore 220A, so as to obtain a form of a second roll 220. Here, in takingup, cowinding using a suitable spacer may be carried out.

In this manner, by passage of the long substrate from the first roll 210through the application apparatus 211A, the drying furnace 212A, thepolarized light UV radiating apparatus 213A, the application apparatus211B, the drying furnace 212B, and the light radiating apparatus 213B inthis order, the long retardation film can be continuously produced by aroll-to-roll process.

In the production method shown in FIG. 1, a method of continuousproduction from the long substrate to the long retardation film has beenshown. Alternatively, however, the long substrate may be passed, forexample, from the first roll 210 through the application apparatus 211A,the drying furnace 212A, and the polarized light radiating apparatus213A in this order and taken up onto a roll core for continuousproduction of a long alignment film in a roll form, and thereafter, theobtained long alignment film in a roll form may be paid out and passedthrough the application apparatus 211B, the drying furnace 212B, and thelight radiating apparatus 213B in this order, thereby to produce a longretardation film.

When the long retardation film is produced in a form of the second roll220, the long retardation film may be paid out from the second roll 220and cut into a predetermined dimension, whereafter a polarizing film maybe bonded onto the cut retardation film to produce a circularlypolarizing plate. Alternatively, however, a long circularly polarizingplate can be continuously produced by preparing a third roll on which along polarizing film has been taken up onto a roll core.

With reference to FIG. 3, a method of continuously producing a longcircularly polarizing plate will be described. Such a production methodincludes:

continuously paying out a long retardation film of the present inventionfrom a second roll 220 and continuously paying out a long polarizingfilm from a third roll 230 on which the long polarizing film has beentaken up;

continuously bonding the long retardation film and the long polarizingfilm to obtain a long circularly polarizing plate; and

taking up the obtained long circularly polarizing plate onto a fourthroll core 240A so as to obtain a fourth roil 240.

This method is what is known as roll-to-roll bonding. The longretardation film and the long polarizing film can be bonded with use ofa suitable adhesive agent.

The long substrate or the long substrate and the long optical alignmentmembrane may be peeled off before or after taking up the obtained longcircularly polarizing plate onto the fourth roll core.

By peeling the long substrate off, the long circularly polarizing platemade of the long optical alignment membrane, the long retardationmembrane, and the long polarizing films is obtained.

By peeling the long substrate and the long optical alignment membraneoff, the long circularly polarizing plate made of the long retardationmembrane and the long polarizing film is obtained.

FIG. 4 is a view describing a method of continuously peeling the longsubstrate or the long substrate and the long optical alignment membraneoff before taking up the obtained long circularly polarizing plate ontothe fourth roll core 240A.

Such a production method includes:

continuously paying out a long retardation film of the present inventionfrom a second roll 220 and continuously paying out a long polarizingfilm from a third roll 230 on which the long polarizing film has beentaken up;

continuously bonding the long retardation film and the long polarizingfilm to obtain a long circularly polarizing plate;

peeling the long substrate or the long substrate and the long opticalalignment membrane of the obtained long circularly polarizing plate offat a guide roll 270, so as to separate into the long substrate and thelong circularly polarizing plate made of the long optical alignmentmembrane, the long retardation membrane, and the long polarizing film,or separate into the long substrate and the long optical alignmentmembrane, and the long circularly polarizing plate made of the longretardation membrane and the long polarizing film; and

taking up the long circularly polarizing plate made of the long opticalalignment membrane, the long retardation membrane, and the longpolarizing film or the long circularly polarizing plate made of the longretardation membrane and the long polarizing film onto a fifth roll core250A, so as to obtain a fifth roll 250, while taking up the peeled longsubstrate or the peeled long substrate and long optical alignmentmembrane onto a sixth roll core 260A so as to obtain a sixth roll 260.

FIG. 5 is a view describing a method of continuously peeling the longsubstrate or the long substrate and the long optical alignment membraneoff after taking up the obtained long circularly polarizing plate ontothe fourth roll core 240A.

Such a production method includes:

continuously paying out the long circularly polarizing plate of thepresent invention from the fourth roll 240;

peeling the long substrate or the long substrate and the long opticalalignment membrane of the long circularly polarizing plate off at aguide roll 270, so as to separate into the long substrate and the longcircularly polarizing plate made of the long optical alignment membrane,the long retardation membrane, and the long polarizing film, or separateinto the long substrate and the long optical alignment membrane, and thelong circularly polarizing plate made of the long retardation membraneand the long polarizing film; and

taking up the long circularly polarizing plate made of the long opticalalignment membrane, the long retardation membrane, and the longpolarizing film or the long circularly polarizing plate made of the longretardation membrane and the long polarizing film onto a fifth roll core250A, so as to obtain a fifth roll 250, while taking up the peeled longsubstrate or the peeled long substrate and long optical alignmentmembrane onto a sixth roll core 260A so as to obtain a sixth roll 260.

The long retardation film of the present invention can be cut inaccordance with the needs and used in various display devices. Thedisplay device is a device having a display element and includes alight-emitting element or a light-emitting device as a light-emittingsource. The display device may be, for example, a liquid crystal displaydevice, an organic electroluminescence (EL) display device, an inorganicelectroluminescence (EL) display device, an electron emission displaydevice (for example, a field emission display device (FED), asurface-conduction electron-emitter display device (SED)), an electronicpaper (display device using an electronic ink or an electrophoresiselement), a plasma display device, a projection-type display device (forexample, a grating light valve (GLV) display device, a display devicehaving a digital micromirror device (DMD)), a piezoelectric ceramicdisplay, or the like. The liquid crystal display devices are meant toinclude all of a transmission liquid crystal display device, asemitransmission liquid crystal display device, a reflection liquidcrystal display device, a direct-view liquid crystal display device, aprojection liquid crystal display device, and the like. These displaydevices maybe either a display device that displays a two-dimensionalimage or a stereographic display device that displays athree-dimensional image.

Also, the long circularly polarizing plate can be cut in accordance withthe needs and used effectively for a display device such as an organicelectroluminescence (EL) display device or an inorganicelectroluminescence (EL) display device, in particular.

EXAMPLES

Hereafter, the present invention will be described in further moredetail by way of Examples. In the Examples, “%” and “part(s)” represent“mass %” and “part(s) by mass”, respectively, unless otherwisespecified.

Example 1 [Production of Optical Alignment Membrane Forming Composition]

The following components were mixed, and the obtained mixture wasstirred at 80° C. for 1 hour to obtain an optical alignment membraneforming composition.

Optical alignment material (5 parts):

Solvent (95 parts): cyclopentanone

[Production of Liquid Crystal Cured Membrane Forming Composition]

The following components were mixed and stirred at 80° C. for 1 hour toobtain a liquid crystal cured membrane forming composition.

Polymerizable liquid crystal compound; compound (A11-1) 100 parts

Polymerizable liquid crystal compound; compound (x-1)  33 parts

Polymerization initiator;2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butane-1-one (Irgacure(registered trademark) 369;  8 manufactured by BASF JAPAN Ltd.) partsLevelling agent; polyacrylate compound (BYK-361N; manufactured byBYK-Chemie GmbH)  0.1 parts Other additives; LALOMER LR9000(manufactured by BASF JAPAN Ltd.)  6.7 parts Solvent; cyclopentanone 546parts Solvent; N-methylpyrrolidone 364 parts

[Production, of Long Retardation Film]

The surface of a cycloolefin polymer film roll (ZF-14, manufactured byZEON CORPORATION) was treated once by using a plasma processingapparatus (manufactured by Sekisui Chemical Co., Ltd.) under conditionswith an intensity of 1.5 J/cm² and an added oxygen concentration of0.25%.

Subsequently, the optical alignment membrane forming composition wasapplied onto the above film surface by the die coating method, therebyto obtain a first application membrane. The obtained first applicationmembrane was dried at 100° C. for 2 minutes and thereafter cooled toroom temperature, thereby to obtain a first dried coating membrane.Thereafter, polarized ultraviolet light was radiated at 100 mJ ( 313 nmstandard) so that the direction of the alignment restricting force wouldform an angle of 45° relative to the transportation direction of theabove film, thereby to form a long optical alignment membrane on theabove film. The polarized ultraviolet light was radiated onto the firstdried coating membrane in a direction perpendicular to the lengthdirection and the lateral direction of the first dried coating membrane.

The liquid crystal cured membrane forming composition was applied ontothe long optical alignment membrane by the die coating method to obtaina second application membrane so that the membrane thickness of thesecond application membrane would be 17 μm. The second applicationmembrane was subjected to heated drying at 120° C. for 2 minutes andcooled to room temperature to obtain a second dried coating membrane.Ultraviolet light with an exposure amount of 1000 mJ/cm² (355 nmstandard) was radiated onto the second dried coating membrane by usingan ultraviolet light radiating apparatus, thereby to obtain a longretardation film (1) having a retardation membrane formed thereon.

[Membrane Thickness Measurement]

A film piece (4 cm×4 cm) at an arbitrary site was cut out from the longretardation film (1), and the membrane thickness was measured by using alaser microscope (LEXT3000, manufactured by Olympus Corporation). As aresult of this, the membrane thickness of the long alignment membranewas 50 nm, and the membrane thickness of the long retardation membranewas 2.1 μm.

[Measurement of Haze]

A film piece (4 cm×4 cm) at an arbitrary site was cut out from the longretardation film (1), and the haze value was measured by using ahazemeter (HZ-2; manufactured by Suga Test Instruments Co., Ltd.). As aresult of this, the haze value was 0.2%.

[Measurement of Retardation Value]

A film piece (4 cm×4 cm) at an arbitrary site was cut out from the longretardation film (1), and the front retardation value at a wavelength of587.7 nm was measured by using a birefringence measuring apparatus(KOBRA-WR, manufactured by Oil Scientific Instruments), with a result of148 nm. Here, since the cycloolefin polymer film used in the longsubstrate does not have a birefringence property, the result obtained bymeasurement in a mode of including the substrate refers to the frontretardation value of the retardation membrane formed on the substrate.

[Measurement of Wavelength Dispersion Property]

A film piece (4 cm×4 cm) at an arbitrary site was cut out from the longretardation film (1), and the front retardation values at wavelengths of450.9 nm, 498.6 nm, 549.4 nm, 587.7 nm, 627.8 nm, and 751. 3 nm weremeasured by using a birefringence measuring apparatus (KOBRA-WR,manufactured by Oji Scientific Instruments), with a result of 130 nm,142 nm, 147 nm, 148 nm, 149 nm, and 151 nm, respectively. The frontretardation values at wavelengths of 450 nm, 550 nm, and 650 nm, ascalculated by Sellmeier fitting, were 129 nm, 141 nm, and 144 nm,respectively. This has confirmed that the relationships ofRe(450)/Re(550)=0.91≦1 and Re(650)/Re(550)=1.02≧1 are satisfied.

[Integral Lamination with Long Polarizing Film]

The liquid crystal cured membrane side of the long retardation film (1)and an iodine-PVA polarizing plate roll (SRW842A; manufactured bySumitomo Chemical Co., Ltd., the absorption axis coincides with thetransportation direction of the roll) were integrally laminated via apressure-sensitive adhesive agent, so as to obtain a long circularlypolarizing plate (1).

[Measurement of Reflectivity]

In order to confirm the usefulness of the long circularly polarizingplate (1), a film piece (4 cm×4 cm) at an arbitrary site was cut outfront the long circularly polarizing plate (1), so as to obtain acircularly polar i zing plate. The reflectivity of the circularlypolarizing plate was measured in the following manner. The surface ofthe fabricated circularly polarizing plate on the side deriving from thelong retardation film (1) and a reflection plate (mirror surfacealuminum plate) were bonded by using a pressure-sensitive adhesiveagent, thereby to fabricate a measurement sample.

By using a spectrophotometer (UV-3150 manufactured by ShimadzuCorporation), light having a wavelength within a range of 400 to 700 nmwas allowed to be incident at 12° of the normal direction into themeasurement sample at a step of 2 nm, and the reflectivity of thereflected light was measured. When comparison was made by assuming thatthe reflectivity as measured by disposing only the reflection platewithout bonding the circularly polarizing plate was 100%, the lightwithin the range of 400 to 700 nm was about 1% to 10% for all of thewavelengths, thereby confirming that a sufficient antireflectionproperty was obtained over the whole visible light region.

Example 2 [Production of Long Retardation Film]

The optical alignment membrane forming composition was applied onto asurface of a polyethylene terephthalate film roll (DIAFOIL T140E25,manufactured by Mitsubishi Plastics, Inc.) by the die coating method,thereby to obtain a first application membrane. The obtained firstapplication membrane was dried at 100° C. for 2 minutes and thereaftercooled to room temperature, thereby to obtain a first dried coatingmembrane. Thereafter, polarized ultraviolet light was radiated at 100 mJ(313 nm standard) so that the direction of the alignment restrictingforce would form an angle of 45° relative to the transportationdirection of the above film, thereby to form; a long optical alignmentmembrane on the above film. The polarized ultraviolet light was radiatedonto the first dried coating membrane in a direction perpendicular tothe length direction and the lateral direction of the first driedcoating membrane.

The liquid crystal cured membrane forming composition was applied ontothe long optical alignment membrane by the die coating method to obtaina second application membrane so that the membrane thickness of thesecond application membrane would be 17 μm. The second applicationmembrane was subjected to heated drying at 120° C. for 2 minutes andcooled to room temperature to obtain a second dried coating membrane.Ultraviolet light with an exposure amount of 1000 mJ/cm² (365 nmstandard) was radiated onto the second dried coating membrane by usingan ultraviolet light radiating apparatus, thereby to obtain a longretardation film (2) having a retardation membrane formed thereon.

[Peeling-Off of Substrate Film]

A corona treatment was carried out on the retardation membrane surfaceof the long retardation film (2), and a cycloolefin polymer film roilwas stacked via a pressure-sensitive adhesive layer. Subsequently, thepolyethylene terephthalate film and the first dried coating membranewere peeled off by using a line having an essential part shown in FIG.4, thereby to obtain a long retardation film (3) made of the retardationmembrane, the pressure-sensitive adhesive layer, and the cycloolefinpolymer film.

[Membrane Thickness Measurement]

A film piece (4 cm×4 cm) at an arbitrary site was cut out from the longretardation film (3), and the membrane thickness was measured by using alaser microscope (LEXT3000, manufactured by Olympus Corporation). As aresult of this, the membrane thickness of the long retardation membranewas 2.2 μm.

[Measurement of Haze]

A film piece (4 cm×4 cm) at an arbitrary site was cut out from the longretardation film (3), and the haze value was measured by using ahazemeter (HZ-2; manufactured by Suga Test Instruments Co., Ltd.). As aresult of this, the haze value was 0.4%.

[Measurement of Retardation Value]

A film piece (4 cm×4 cm) at an arbitrary site was cut out from the longretardation film (3), and the front retardation value at a wavelength of587.7 nm was measured by using a birefringence measuring apparatus(KOBRA-WR, manufactured by Oji Scientific Instruments), with a result of143 nm. Here, since the cycloolefin polymer film used in the longsubstrate does not have a birefringence property, the result obtained bymeasurement in a mode of including the substrate refers to the frontretardation value of the retardation membrane formed on the substrate.

[Measurement of Wavelength Dispersion Property]

A film piece (4 cm×4 cm) at an arbitrary site was cut out from the longretardation film (3), and the front retardation values at wavelengths of450.9 nm, 498.6 nm, 549.4 nm, 587.7 nm, 627.8 nm, and 751.3 nm weremeasured by using a birefringence measuring apparatus (KOBRA-WR,manufactured by Oji Scientific Instruments), with a result of 125 nm,137 nm, 142 nm, 143 nm, 144 nm, and 146 nm, respectively. The frontretardation values at wavelengths of 450 nm, 550 nm, and 650 nm, ascalculated by Sellmeier fitting, were 124 nm, 136 nm, and 139 nm,respectively. This has confirmed that the relationships ofRe(450)/Re(550)=0.91≦1 and Re(650)/Re(550)=1.02≧1 are satisfied.

[Integral Lamination with Long Polarizing Film]

The retardation membrane side of the long retardation film (3) and aniodine-PVA polarizing plate roll (SRW842A; manufactured by SumitomoChemical Co., Ltd., the absorption axis coincides with thetransportation direction of the roll) were integrally laminated via apressure-sensitive adhesive agent, so as to obtain a long circularlypolarizing plate (3).

[Measurement of Reflectivity]

In order to confirm the usefulness of the long circularly polarizingplate (3), a film piece (4 cm×4 cm) at an arbitrary site was cut outfrom the long circularly polarizing plate (3), so as to obtain acircularly polarizing plate. The reflectivity of the circularlypolarizing plate was measured in the following manner. The surface ofthe fabricated circularly polarizing plate on the side deriving from thelong retardation film (3) and a reflection plate (mirror surfacealuminum plate) were bonded by using a pressure-sensitive adhesiveagent, thereby to fabricate a measurement sample.

By using a spectrophotometer (UV-3150 manufactured by ShiraadzuCorporation), light having a wavelength within a range of 400 to 700 nmwas allowed to be incident at 12° of the normal direction into themeasurement sample at a step of 2 nm, and the reflectivity of thereflected light was measured. When comparison was made by assuming thatthe reflectivity as measured by disposing only the reflection platewithout bonding the circularly polarizing plate was 100%, the lightwithin the range of 400 to 700 nm was about 1% to 10% for all of thewavelengths, thereby confirming that a sufficient antireflectionproperty was obtained over the whole visible light region.

Example 3 [Fabrication of Long Circularly Polarizing Plate (4)]

The retardation membrane surface of the long retardation film (2)obtained in Example 2 was subjected to a corona treatment and integrallylaminated onto an iodine-PVA polarizing plate roll (SRW842A;manufactured by Sumitomo Chemical Co., Ltd., the absorption axiscoincides with the transportation direction of the roll) via apressure-sensitive adhesive agent. Subsequently, the polyethyleneterephthalate film and the first dried coating membrane were peeled offby using a line having an essential part shown in FIG. 5, thereby toobtain a long circularly polarizing plate (4) made of the retardationmembrane, the pressure-sensitive adhesive layer, and the polarizingplate.

[Measurement of Reflectivity]

In order to confirm the usefulness of the long circularly polarizingplate (4), a film piece (4 cm×4 cm) at an arbitrary site was cut outfrom the long circularly polarizing plate (4), so as to obtain acircularly polarizing plate. The reflectivity of the circularlypolarizing plate was measured in the following manner. The surface ofthe fabricated circularly polarizing plate on the side deriving from thelong retardation film (2) and a reflection plate (mirror surfacealuminum plate) were bonded by using a pressure-sensitive adhesiveagent, thereby to fabricate a measurement sample.

By using a spectrophotometer (UV-3150 manufactured by ShimadzuCorporation), light having a wavelength within a range of 400 to 700 nmwas allowed to be incident at 12° of the normal direction into themeasurement sample at a step of 2 nm, and the reflectivity of thereflected light was measured. When comparison was made by assuming thatthe reflectivity as measured by disposing only the reflection platewithout bonding the circularly polarizing plate was 100%, the lightwithin the range of 400 to 700 nm was about 1% to 10% for all of thewavelengths, thereby confirming that a sufficient antire flectionproperty was obtained over the whole visible light region.

The present invention is useful for producing a long retardation filmhaving an optical axis in an oblique direction relative to the lengthdirection of the long retardation film.

1. A method for producing a long retardation film, comprising, in thisorder: (1) continuously applying an optical alignment membrane formingcomposition onto a long substrate to form a first application membraneon the long substrate; (2) drying the first application membrane to forma first dried coating membrane; (3) radiating a polarized light which ispolarized in an oblique direction relative to a length direction of thelong substrate, onto the first dried coating membrane, so as to form along optical alignment membrane in which a direction of an alignmentrestricting force is oblique relative to the length direction of thelong substrate; (4) continuously applying onto the long opticalalignment membrane a liquid crystal cured membrane forming compositioncontaining a polymerizable liquid crystal compound, so as to form asecond application membrane on the long optical alignment membrane; (5)drying the second application membrane to form a second dried coatingmembrane; and (6) curing the second dried coating membrane to form along retardation membrane.
 2. The method for producing a longretardation film according to claim 1, further comprising, after the(6): (7) transcribing the long retardation membrane or the long opticalalignment membrane and the long retardation membrane onto a longtranscription substrate via a pressure-sensitive adhesive agent, so asto obtain a long retardation film made of the long transcriptionsubstrate, a pressure-sensitive adhesive layer, and the long retardationmembrane or a long retardation film made of the long transcriptionsubstrate, a pressure-sensitive adhesive layer, the long retardationmembrane, and the long optical alignment membrane.
 3. The method forproducing a long retardation film according to claim 1, wherein thepolymerizable liquid crystal compound is a compound represented by thefollowing formula (A):

[X¹ represents an oxygen atom, a sulfur atom, or NR¹—; R¹ represents ahydrogen atom or an alkyl group having a carbon number of 1 to 4; Y¹represents a monovalent aromatic hydrocarbon group having a carbonnumber of 6 to 12 and optionally having a substituent or a monovalentaromatic heterocyclic group having a carbon number of 3 to 12 andoptionally having a substituent; Q³ and Q⁴ each independently representa hydrogen atom, a monovalent aliphatic hydrocarbon group having acarbon number of 1 to 20 and optionally having a substituent, amonovalent alicyclic hydrocarbon group having a carbon number of 3 to20, a monovalent aromatic hydrocarbon group having a carbon number of 6to 20 and optionally having a substituent, a halogen atom, a cyanogroup, a nitro group, —NR²R³, or —SR², or Q³ and Q⁴ are bonded with eachother to form an aromatic ring or an aromatic heterocyclic ring togetherwith carbon atoms to which these are bonded; R² and R³ eachindependently represent a hydrogen atom or an alkyl group having acarbon number of 1 to 6; D¹ and D² each independently represent a singlebond, —C(═O)—O—, —C(═S)—O—, —CR⁴R⁵—, —CR⁴R⁵—CR⁶R⁷—, —O—CR⁴R⁵—,—CR⁴R⁵—O—CR⁶R⁷—, —CO—O—CR⁴R⁵—, —O—CO—CR⁴R⁵—, —CR⁴R⁵—O—CO—CR⁶R⁷—,—CR⁴R⁵—CO—O—CR⁶R⁷—, NR⁴—CR⁵R⁶—, or CO—NR⁴ 13 ; R⁴, R⁵, R⁶, and R⁷ eachindependently represent a hydrogen atom, a fluorine atom, or an alkylgroup having a carbon number of 1 to 4; G¹ and G² each independentlyrepresent a divalent alicyclic hydrocarbon group having a carbon numberof 5 to 8, where a methylene group constituting the alicyclichydrocarbon group may be substituted with an oxygen atom, a sulfur atom,or NH—, and a methine group constituting the alicyclic hydrocarbon groupmay be substituted with a tertiary nitrogen atom; and L¹ and L² eachindependently represent a monovalent organic group, where at least oneof L¹ and L² has a polymerizable group].
 4. A long retardation filmcomprising a long substrate, a long optical alignment membrane, and along retardation membrane in this order, wherein a direction of analignment restricting force of the long optical alignment membrane isoblique relative to a length direction of the long substrate, athickness of the long retardation membrane is 3 μm or less, and adirection of an optical axis of the long retardation membrane is obliquerelative to the length direction of the long substrate.
 5. The longretardation film according to claim 4, having a wavelength dispersionproperty satisfying the following formulas (1), (2), and (3):Re(450)/Re(550)≦1.00   (1)1.00≦Re(650)/Re(550)   (2)100<Re(550)<160   (3) wherein, in the formulas, Re(λ) represents anin-plane retardation value relative to a light having a wavelength of λnm.
 6. A method for producing a long circularly polarizing plate,comprising, in this order: (1) continuously applying an opticalalignment membrane forming composition onto a long substrate to form afirst application membrane on the long substrate; (2) drying the firstapplication membrane to form a first dried coating membrane; (3)radiating a polarized light which is polarized in an oblique directionrelative to a length direction of the long substrate, onto the firstdried coating membrane, so as to form a long optical alignment membranein which a direction of an alignment restricting force is obliquerelative to the length direction of the long substrate; (4) continuouslyapplying onto the long optical alignment membrane a liquid crystal curedmembrane forming composition containing a polymerizable liquid crystalcompound, so as to form a second application membrane on the longoptical alignment membrane; (5) drying the second application membraneto form a second dried coating membrane; (6) curing the second driedcoating membrane to form a long retardation membrane; and (8) bonding along polarizing film onto the long retardation membrane.
 7. The methodfor producing a long circularly polarizing plate according to claim 6,further comprising, after the (8): (9) peeling the long substrate or thelong substrate and the long optical alignment membrane off.
 8. Themethod for producing a long circularly polarizing plate according toclaim 6, further comprising, after the (8) or (9): (10) cutting the longcircularly polarizing plate into pieces.
 9. A long circularly polarizingplate in which a long retardation film according to claim 4 and a longpolarizing film are stacked.